[Subrenal capsule assay using nude mice].

Abstract

Six-day subrenal capsule assay (SRCA) using normal immunocompetent mice developed by Bogden et al. is a promising in vivo chemosensitivity test. This method, however, has a problem of influence of the host reaction. We compared the tumor growth kinetics and host reaction between normal immunocompetent and nude mice. The tumor diameter increased until day 6 in normal and day 16 in nude mice, respectively. However the histological finding revealed many host reactive cells and few viable tumor cells on day 6 in normal mice, and well preserved tumour cells on day 16 in nude mice. These results were supported by flow cytometrical analysis. Then, we examined two immunosuppressive drugs; cyclophosphamide (EX) and cyclosporin A (CSA) in SRCA. The tumors increased in the diameter until day 16 in both EX and CSA-treated groups, but the results of the histological examination showed that tumor cells were preserved in tissue on day 14 in CSA-treated and day 6 in EX-treated group. These results were also supported by flow cytometrical analysis. From the investigation of antitumour activities of adriamycin (ADR) and mitomycin C, it was suggested that the 12-day assay was suitable if nude mice were used in SRCA, and six-day assay also, if EX-treated normal mice were used. In CSA-treated group, more toxicity of anticancer drugs was manifested than usual. We studied whether or not CSA had a usefulness in SRCA with normal immunocompetent mice. Sixty mg/kg of CSA was given to BDF1 mice daily SC, and various dosage of ADR was given i.v. on day 2. The body weight of BDF1 mice decreased over 20% within 10 days when ADR was given at more than 5 mg/kg. MX-1, a human breast carcinoma cell line, is known to be sensitive to ADR. This tumor was implanted SC in the back of BALB/c nu/nu mice and chemosensitivity was tested against ADR. ADR resulted to be positive at the dose of 8 mg/kg. On the other hand, the dose of 5 mg/kg proved to be negative, and hence the result of SRCA would be false negative, if the dose of ADR is reduced to avoid the toxicity of CSA. The tumor grew slowly when only 60 mg/kg of CSA was given daily for three weeks, and the inhibition rate was 56.2%. The toxicity of CSA was neglected because the body weight loss was approximately 13%. CSA may have the antitumor effect by itself, and EX did not suppress the host reaction sufficiently.(ABSTRACT TRUNCATED AT 400 WORDS)